1. Field of the Invention
The present invention relates to a micro-lithographic method and apparatus for non-planar workpieces. More particularly, the present invention relates to a micro-lithographic method and apparatus using an energy transparent tubular member selectively coated with an energy opaque layer to selectively expose/mask a resist material on a non-planar workpiece to an energy source. It can also be a physical mask such that material deposition (such as sputtering) is done through the aperture and blocked by the rest of the mask to form the pattern with actual deposited material instead of exposing a layer of resist over material to be etched later.
2. Prior Art
Lithographic techniques have been utilized for some time in the manufacture especially of integrated circuit boards and semiconductor devices and related products. The products manufactured have typically included planar surfaces to which the lithographic techniques were applied. Such techniques have proven extremely effective in the precise manufacturing and formation of very small details in the product. However, attempts to apply such techniques to other than planar surfaces have proven difficult, if not unachievable, until recently. With recent developments in nonplanar lithography, the fabrication of microstructures, including both three-dimensional mechanical parts and three-dimensional electrical components, has become more readily achievable. U.S. Pat. No. 5,106,455, issued Apr. 21, 1992, to Jacobsen et al., which is herein incorporated by reference, discloses a method and apparatus for fabricating microstructures using nonplanar, exposure beam lithography. Using this method and apparatus, very fine, precise and detailed physical structures can be formed on very small three-dimensional objects such as, for example, cylinders. U.S. Pat. No. 5,269,882, issued Dec. 14, 1993, to Jacobsen, which is herein incorporated by reference, discloses a method and apparatus for fabricating thin-film semiconductor devices using nonplanar, exposure beam lithography. In particular, a variety of semiconductor devices can be formed on three-dimensional substrates, again such as cylinders. The methods and apparatus disclosed in the above two patents provide for fabrication of individual microstructures or thin-film semiconductor devices in a type of batch processing approach. U.S. Pat. No. 5,273,622, issued Dec. 29, 1993, to Jacobsen, which is herein incorporated by reference, discloses a continuous processing approach for fabricating microstructures and thin-film semiconductor devices. Such microstructures are finding use in a variety of areas including medical devices, robotics, navigation equipment, motors and similar equipment. U.S. Pat. No. 5,481,184, issued Jan. 2, 1996, to Jacobsen, which is herein incorporated by reference, discloses a system for movement actuators and sensors on very small mechanical parts, such as fibers and filaments. U.S. Pat. No. 5,270,485, issued Dec. 14, 1993, to Jacobsen, which is herein incorporated by reference, discloses a three-dimensional circuit structure with electrical components formed on the surfaces of elongated cylindrical substrates. With the development of these very small (termed xe2x80x9cmicroxe2x80x9d) mechanical devices and electrical elements, the ability to fabricate detailed features of such devices and elements in an efficient and precise way is greatly desired.
The problems faced in fabricating detailed features of these microstructures include the extremely small size of the features and structures and also the nonplanar nature of the structures. In addition, the structures may be relatively long and flexible. Furthermore, the fabrication process can also be very time consuming. For example, resist material is deposited on filamentary substrates which is patterned by exposing the resist material to an energy beam. The substrates are processed one at a time and the resist material is exposed by xe2x80x9cwritingxe2x80x9d the pattern on the substrate with the energy beam. This process of writing the patterns on the substrates and processing the substrates one at a time is very time consuming. Therefore, faster fabrication methods are desired.
It is a feature of the present invention to provide a method and apparatus for fabricating microstructures utilizing lithographic techniques.
It is another feature of the present invention to provide such a method and apparatus which allows the fabrication of details over nonplanar surface areas of a workpiece, or filamentary substrate.
It is yet another feature of the present invention to provide such a method and apparatus in which the whole pattern in a resist material may be exposed all at once, or nearly all at once.
It is a further feature of the present invention to provide a method and apparatus for direct deposition of material on a non-planar workpiece in a desired pattern.
These and other features and advantages of the present invention are realized in an apparatus having an energy-transparent tubular member with a hollow for receiving a filamentary substrate and a layer of energy-opaque material selectively coating the tubular member to form the desired pattern. The filamentary substrate is coated with an energy resist material. The tubular member is made of a material that is transparent to the type of energy used and has an elongated hollow for holding the filamentary substrate. The layer of material coating of the tubular member (either on the outside or inside of the tubular member) is opaque to the type of energy used and is patterned to selectively mask portions of the resist material on the filamentary substrate.
The apparatus may also include an energy source for exposing the resist and a collet or holding device for holding the tubular member. The collet may be coupled to a motor for rotating the tubular member and filamentary substrate before the energy source. Alternatively, the holding device may be configured to be disposed in a fixture for exposing the resist.
An alternative embodiment of the apparatus has an energy-opaque tubular member with a hollow for receiving a filamentary substrate and apertures formed in the walls of the tubular member to form the desired pattern. In this embodiment, the tubular member is made of a material that is opaque to the type of energy used, rather than transparent.
Another alternative embodiment of the invention is to provide a physical mask that blocks the applied energy from reaching a filamentary substrate except for areas that have apertures formed in the mask.